1. Field of the Invention
The present invention relates to vehicle engine controls including automated start and stop control systems responsive to battery voltage levels and enabling an adjustment to the battery voltage threshold in response to a detection of changing ambient air temperature.
2. Background Art
An engine electronic control module may include an automated start and stop idle function. The control uses data to continuously monitor inputs such as engine temperature and battery voltage. During periods when the vehicle is not moving, the system automatically starts and stops the engine as necessary to maintain the temperature of the fuel in the engine at a desirable level for combustion and battery voltage within defined limits.
In one known unit, a driver enables the automated start and stop feature by shifting the transmission to neutral (and high range, if available), setting the parking brake and turning cruise control on while the engine is idling. The hood/engine compartment doors must also be closed. Once the idle shutdown timer expires in the control, the feature takes control until the next time the vehicle is driven, or until an operator simply turns off the ignition to disable the automated start and stop features.
A previously known system also includes an optional thermostat for tractors equipped with a sleeper berth that allows automated start and stop features to maintain cab temperature in the desired range. It is also available for coach applications to keep the interior temperature within the desired range. The thermostat has a lighted display and control panel for easy use and may be switched off if controlling interior temperature is not desired. The driver sets the desired interior temperature. Three driver-selectable “comfort zone” settings control thermostat sensitivity. A small zone will closely maintain temperature while a larger zone results in greater savings by commanding the engine to start and run less frequently. Continuous idling is allowed at extreme outside temperatures. However, a limited number of inputs may result in increased fuel usage without additional control responses to conditions that may occur.
A continuous run control was previously known to allow the engine to run continuously if the outside temperature parameter exceeds the factory set limits (hot and cold) and the thermostat set point can not be met (factory default is 25° F. (−3.88° C.) for cool mode and 90° F. (32° C.) for heat mode). When the thermostat is in the Continuous Run Condition, the thermometer icon will flash along with the heating or cooling icon. However, such systems have set values for thresholds that do not adjust for changing responsiveness of the automatic start and stop operation.
If the conditions triggering Continuous Run Control are not met and the thermostat set point is not met within 45 minutes, the engine will shut down for 15 minutes, restart and run for 15 minutes. This 15 minute on and off cycle will continue until the thermostat set point is reached or until the thermostat is turned off. If automatic start and stop idle enters the extended idle mode of operation, the heat or cool setting on the thermostat may not match the vehicle heating or cooling system setting. Such operation could also be an indication of low freon, blockage in the heater system, or system tampering.